Technical Field
The embodiments herein generally relate to chemical detection systems, and more particularly to optical techniques used for detecting chemicals.
Description of the Related Art
Benchtop Raman spectrometers are analytical tools for the detection or identification of unknown solids and liquids. The extension of this technology to handheld systems for trace concentrations of vapor-phase chemicals is extremely important for applications ranging from breath analysis to environmental monitoring to chemical warfare agent detection. The miniaturization of gas-phase detection systems is hindered by the extremely weak Raman signal generated from a dilute vapor over short interaction lengths. Recent improvements towards this end have used resonant cavities or multipass cells that are tens of centimeters long, but these designs are not likely to be implemented in an inexpensive, handheld platform. An enhancement of Raman signals from multicomponent vapors using hollow-core optical fibers have shown part-per-million (ppm) detection limits, but these systems suffer from cumbersome techniques for removing analytes from the fiber after exposure.